The present invention relates to a device for taking up the leading end of a new roll of strip material and transferring it to a successive work station.
Italian patent application no 3334 A/83 discloses a machine capable of replacing a first roll of strip material with a second roll automatically, provided that the leading end of the new roll is arranged by hand previously in a prescribed take-up position.
If a higher level of automation is to be achieved, on the other hand, the machine must be capable of positioning the leading end of the new roll in the take-up configuration without manual assistance. In effect, there are various examples of apparatus in current use capable of performing this operation automatically.
A first apparatus of the general type in question, disclosed and claimed in U.S. Pat. No. 4,695,007, comprises a rotating disk supporting a pair of rolls disposed mutually parallel and in diametrical opposition relative to the axis of the disk, a cutting device by means of which to break the seal of the new roll (typically, a sticker by which the leading end of the new strip is secured to the cylindrical surface of the roll), feed means by which the leading edge of the new strip is carried forward and positioned, and a station at which the leading end of the new strip is cut and spliced to the trailing end of the strip currently in use by relative devices. The rolls themselves, one normally in use and the other standing by as its replacement, can be driven about respective axes disposed parallel to the axis of rotation of the supporting disk, turning in both directions concurrently with feed and positioning means that consist in a plurality of mini-conveyor belts positioned with one end beneath the new roll.
The cutting device, positioned beneath and in close proximity to the new roll, comprises a first swing arm rotatable about an axis parallel to that of the disk and carrying a roller designed to enter into tangential contact with the roll, means by which to sense the sticker, and a second swing arm pivotably associated with the first swing arm, rotatable about an axis perpendicular to the axis of the disk and carrying a blade capable of motion in a plane substantially tangential to the new roll in such a way as to intercept and sever the sticker. The splicing device, which extends from the end of the mini-conveyor belts remote from the new roll, comprises a bar capable of swinging transversely to the direction of movement of the belts. Such a bar exhibits a plurality of holes connected to a source of negative pressure and is capable of movement, produced by respective supporting arms, between a lowered receiving position, in which the surface of the bar functions as an extension of the conveyor belts, and a raised operating position in which the leading end of the strip taken up from the new roll is pressed, together with the trailing end of the strip uncoiled from the depleted roll, against a heated reaction bar. The device further comprises a cutter, positioned alongside the heated reaction bar, by which the depleted strip is intercepted at a point preceding this same bar in relation to the direction followed by the running strip.
At the moment when a roll change occurs, the first arm is rotated to bring the roller and the blade into contact with the surface of revolution of the new roll, the sensing means are activated, and the new roll is set in rotation concurrently with its coiling direction and with the blade skimming the surface. As the sticker is detected by the sensing means, the direction of rotation of the new roll is reversed; the sticker then rotates back toward the cutting edge of the blade, which penetrates between the leading end of the strip and the coil beneath. The activation of the second swing arm now causes the blade to cut through the sticker and free the leading end of the strip whereupon the first arm is returned to its at-rest position, distanced from the roll, and the roll is rotated further in the uncoiling direction. At the same time, the conveyor belts are set in motion, running concurrently and synchronously with the rotation of the roll, in such a way that the roll gradually uncoils and the leading end of the strip is supported and advanced by the belts until encountering further sensing means. Next, the direction of movement both of the conveyor belts and of the roll is reversed in order to position the leading end of the strip correctly on the splicing bar, suction is generated to ensure the stable retention of the strip against the bar, and the splicing bar is raised to a position of interaction with the heated reaction bar, which proceeds to unite the leading end of the new strip with the trailing end of the strip in use. Finally, the cutter is activated to trim off the end of the depleted strip.
In a second apparatus of similar type, disclosed in German patent application no. 35 38 893, the leading end of the new roll of strip is fastened with dabs of gum rather than by a sticker. This apparatus comprises means for separating the gummed surfaces and then holding and advancing the leading end of the new roll; such means consist in a penetrating gripper with two spring loaded jaws, one of which exhibiting a tapered end designed to function as a scraper, the other interacting with the tapered end of the first. More exactly, the first jaw affords a seating to receive one end of the second jaw, of which the relative springs ensure that the first jaw is maintained in a given position.
The penetrating gripper is capable of movement between a first position in which the new roll of strip material, carried by a rocker arm together with the roll in use, is moved into contact with the first jaw, and a second position in which the leading end of the new strip is transferred by the gripper to a device that holds the strip and feeds it on to a successive device by which the leading end is spliced to the trailing end of the depleted strip. At the moment of a changeover, the new roll is moved alongside the penetrating gripper, which will be stationary in the first position, and then set in rotation about its own axis in the uncoiling direction. The first jaw of the gripper continues to occupy the same position until its tapered end, riding against the surface of revolution of the new roll, encounters the leading end of the strip. At this point, the slender edge of the jaw slips under the gummed leading end of the strip and detaches it, levering against the force of the springs which maintain the normal configuration of the gripper. Thereupon, the second jaw snaps against the first, under the action of the relative spring, thereby restraining the leading end of the new strip. The gripper then moves to the second position, where the end of the strip is transferred to the hold and feed device.
The types of apparatus described above are somewhat complicated, structurally and functionally. The object of the present invention is to provide a device of the type in question, such as will ensure simplicity and economy both in construction and in operation.